Sedimentological studies of the "Ilha de Marchantaria" in the Solimões/Amazon River near Manaus

Sedimentological studies on the Ilha de Marchantaria an island in the Amazon river near Manaus reveal the existence of four different structural main units. A: Sandy channel bars consisting of giant ripples constitute deposits for the formation of islands or newly formed areas of the Varzea. B: Gradual accumulation on the channel bars leads to the formation of point bar ridges which consist chiefly of small-scale ripples. C: Between point bar ridges of different ages there exist swales. During rising water level the river water flows from the downward side into the swales where finegrained sediments are deposited. D: Permanent lakes are formed mainly in the centre of the islands. During low water periods the lakes may be cut of from the river. During high water periods when the whole island is flooded by the river, additional sedimentation takes place especially in the upstream area of the island. There is however, extensive erosion of the banks on the upstream side of the island. By erosion of the upstream end and sedimentation processes on the downstream end the island moves slowly downstream

Measurement of atmospheric composition by the ATMOS instrument from Table Mountain Observatory

Following its first flight on board the Space Shuttle 'Challenger' as part of the Spacelab 3 payload, the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument has been operated at the Jet Propulsion Laboratory's Table Mountain Observatory (TMO; 34.4 deg N, 117.7 deg W, 2.23 km altitude) in the San Gabriel Mountains of Southern California. With the delay in the resumption of regular Shuttle flights, ATMOS has acquired a large number of high-quality, high-resolution infrared solar absorption spectra, spanning a period between late-1985 and mid-1990. These spectra are being analyzed to derive the column abundances of several atmospheric species including O_3, HCl, HF, and HNO_3. Although limited in temporal coverage, the preliminary results for these gases are discussed here in the context of the requirement and contribution to be made by similar instruments in detecting long term changes in stratospheric composition

1995 atmospheric trace molecule spectroscopy (ATMOS) linelist

The Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment uses a Fourier-transform spectrometer on board the Space Shuttle to record infrared solar occultation spectra of the atmosphere at 0.01-cm^(-1) resolution. The current version of the molecular spectroscopic database used for the analysis of the data obtained during three Space Shuttle missions between 1992 and 1994 is described. It is an extension of the effort first described by Brown et al. [Appl. Opt. 26, 5154 (1987)] to maintain an up-to-date database for the ATMOS experiment. The three-part ATMOS compilation contains Line parameters of 49 molecular species between 0 and 10000 cm^(-1), The main list, with nearly 700,000 entries, is an updated version of the HITRAN 1992 database. The second compilation contains supplemental line parameters, and the third set consists of absorption cross sections to represent the unresolvable features of heavy molecules. The differences between the ATMOS database and other public compilations are discussed

Trend in ice moistening the stratosphere – constraints from isotope data of water and methane

Water plays a major role in the chemistry and radiative budget of the stratosphere. Air enters the stratosphere predominantly in the tropics, where the very low temperatures around the tropopause constrain water vapour mixing ratios to a few parts per million. Observations of stratospheric water vapour show a large positive long-term trend, which can not be explained by change in tropopause temperatures. Trends in the partitioning between vapour and ice of water entering the stratosphere have been suggested to resolve this conundrum. We present measurements of stratospheric H_(2)O, HDO, CH_4 and CH_(3)D in the period 1991–2007 to evaluate this hypothesis. Because of fractionation processes during phase changes, the hydrogen isotopic composition of H_(2)O is a sensitive indicator of changes in the partitioning of vapour and ice. We find that the seasonal variations of H_(2)O are mirrored in the variation of the ratio of HDO to H_(2)O with a slope of the correlation consistent with water entering the stratosphere mainly as vapour. The variability in the fractionation over the entire observation period is well explained by variations in H_(2)O. The isotopic data allow concluding that the trend in ice arising from particulate water is no more than (0.01±0.13) ppmv/decade in the observation period. Our observations suggest that between 1991 and 2007 the contribution from changes in particulate water transported through the tropopause plays only a minor role in altering in the amount of water entering the stratosphere

Measurement of atmospheric composition by the ATMOS instrument from Table Mountain Observatory

Following its first flight on board the Space Shuttle 'Challenger' as part of the Spacelab 3 payload, the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument has been operated at the Jet Propulsion Laboratory's Table Mountain Observatory (TMO; 34.4 deg N, 117.7 deg W, 2.23 km altitude) in the San Gabriel Mountains of Southern California. With the delay in the resumption of regular Shuttle flights, ATMOS has acquired a large number of high-quality, high-resolution infrared solar absorption spectra, spanning a period between late-1985 and mid-1990. These spectra are being analyzed to derive the column abundances of several atmospheric species including O_3, HCl, HF, and HNO_3. Although limited in temporal coverage, the preliminary results for these gases are discussed here in the context of the requirement and contribution to be made by similar instruments in detecting long term changes in stratospheric composition

Carbon dioxide in the atmosphere: Isotopic exchange with ozone and its use as a tracer in the middle atmosphere

Atmospheric heavy ozone is enriched in the isotopes ^(18)O and ^(17)O. The magnitude of this enhancement, of the order of 100‰, is very large compared with that commonly known in atmospheric chemistry and geochemistry. The heavy oxygen atom in heavy ozone is therefore useful as a tracer of chemical species and pathways that involve ozone or its derived products. As a test of the isotopic exchange reactions, we successfully carry out a series of numerical experiments to simulate the results of the laboratory experiments performed by Wen and Thiemens [1993] on ozone and CO_2. A small discrepancy between the experimental and the model values for ^(17)O exchange is also revealed. The results are used to compute the magnitude of isotopic exchange between ozone and carbon dioxide via the excited atom O(^1D) in the middle atmosphere. The model for ^(18)O is in good agreement with the observed values

A teratocarcinoma-like human embryonic stem cell (hESC) line and four hESC lines reveal potentially oncogenic genomic changes

The first Swiss human embryonic stem cell (hESC) line, CH-ES1, has shown features of a malignant cell line. It originated from the only single blastomere that survived cryopreservation of an embryo, and it more closely resembles teratocarcinoma lines than other hESC lines with respect to its abnormal karyotype and its formation of invasive tumors when injected into SCID mice. The aim of this study was to characterize the molecular basis of the oncogenicity of CH-ES1 cells, we looked for abnormal chromosomal copy number (by array Comparative Genomic Hybridization, aCGH) and single nucleotide polymorphisms (SNPs). To see how unique these changes were, we compared these results to data collected from the 2102Ep teratocarcinoma line and four hESC lines (H1, HS293, HS401 and SIVF-02) which displayed normal G-banding result. We identified genomic gains and losses in CH-ES1, including gains in areas containing several oncogenes. These features are similar to those observed in teratocarcinomas, and this explains the high malignancy. The CH-ES1 line was trisomic for chromosomes 1, 9, 12, 17, 19, 20 and X. Also the karyotypically (based on G-banding) normal hESC lines were also found to have several genomic changes that involved genes with known roles in cancer. The largest changes were found in the H1 line at passage number 56, when large 5 Mb duplications in chromosomes 1q32.2 and 22q12.2 were detected, but the losses and gains were seen already at passage 22. These changes found in the other lines highlight the importance of assessing the acquisition of genetic changes by hESCs before their use in regenerative medicine applications. They also point to the possibility that the acquisition of genetic changes by ESCs in culture may be used to explore certain aspects of the mechanisms regulating oncogenesis

A teratocarcinoma-like human embryonic stem cell (hESC) line and four hESC lines reveal potentially oncogenic genomic changes

The first Swiss human embryonic stem cell (hESC) line, CH-ES1, has shown features of a malignant cell line. It originated from the only single blastomere that survived cryopreservation of an embryo, and it more closely resembles teratocarcinoma lines than other hESC lines with respect to its abnormal karyotype and its formation of invasive tumors when injected into SCID mice. The aim of this study was to characterize the molecular basis of the oncogenicity of CH-ES1 cells, we looked for abnormal chromosomal copy number (by array Comparative Genomic Hybridization, aCGH) and single nucleotide polymorphisms (SNPs). To see how unique these changes were, we compared these results to data collected from the 2102Ep teratocarcinoma line and four hESC lines (H1, HS293, HS401 and SIVF-02) which displayed normal G-banding result. We identified genomic gains and losses in CH-ES1, including gains in areas containing several oncogenes. These features are similar to those observed in teratocarcinomas, and this explains the high malignancy. The CH-ES1 line was trisomic for chromosomes 1, 9, 12, 17, 19, 20 and X. Also the karyotypically (based on G-banding) normal hESC lines were also found to have several genomic changes that involved genes with known roles in cancer. The largest changes were found in the H1 line at passage number 56, when large 5 Mb duplications in chromosomes 1q32.2 and 22q12.2 were detected, but the losses and gains were seen already at passage 22. These changes found in the other lines highlight the importance of assessing the acquisition of genetic changes by hESCs before their use in regenerative medicine applications. They also point to the possibility that the acquisition of genetic changes by ESCs in culture may be used to explore certain aspects of the mechanisms regulating oncogenesis

Isotopic composition of stratospheric ozone

We present a kinetic calculation for the isotopic composition of stratospheric ozone. The calculated enrichments of ^(49)O_3 and ^(50)O_3 are in agreement with atmospheric measurements made at midlatitudes. Integrating the kinetic fractionation processes in the formation and photolysis of ozone, we obtain enrichments of ∼7.5–10.5 and ∼7.5–12.5% (referenced to atmospheric O_2) for δ^(49)O_3 and δ^(50)O_3, respectively, at altitudes between 20 and 35 km; the photolysis in the Hartley band of ozone is responsible for the observed altitude variation. The overall magnitude of the ozone enrichments (∼10%) is large compared with that commonly known in atmospheric chemistry and geochemistry. The heavy oxygen atom in ozone is therefore useful as a tracer of chemical species and pathways that involve ozone or its derived products. For example, the mass anomalies of oxygen in two greenhouse gases, CO_2 and N_2O, are likely the consequences of the transfer of heavy oxygen atoms from ozone

Heavy ozone enrichments from ATMOS infrared solar spectra

Vertical enrichment profiles of stratospheric ^(16)O^(16)O^(18)O and ^(16)O^(18)O^(16)O (hereafter referred to as ^(668)O_3 and ^(686)O_3 respectively) have been derived from space-based solar occultation spectra recorded at 0.01 cm^(−1) resolution by the ATMOS (Atmospheric Trace MOlecule Spectroscopy) Fourier-transform infrared (FTIR) spectrometer. The observations, made during the Spacelab 3 and ATLAS-1, -2, and -3 shuttle missions, cover polar, mid-latitude and tropical regions between 26 to 2.6 mb inclusive (≈ 25 to 41 km). Average enrichments, weighted by molecular ^(48)O_3 density, of (15±6)% were found for ^(668)O_3 and (10±7)% for ^(686)O_3. Defining the mixing ratio of ^(50)O_3 as the sum of those for ^(668)O_3 and ^(686)O_3, an enrichment of (13±5)% was found for ^(50)O_3 (1σ standard deviation). No latitudinal or vertical gradients were found outside this standard deviation. From a series of ground-based measurements by the ATMOS instrument at Table Mountain, California (34.4°N), an average total column ^(668)O_3 enrichment of (17±4)% (1σ standard deviation) was determined, with no significant seasonal variation discernable. Possible biases in the spectral intensities that affect the determination of absolute enrichments are discussed